全文获取类型
收费全文 | 404篇 |
免费 | 19篇 |
国内免费 | 3篇 |
专业分类
安全科学 | 14篇 |
废物处理 | 5篇 |
环保管理 | 73篇 |
综合类 | 87篇 |
基础理论 | 105篇 |
污染及防治 | 91篇 |
评价与监测 | 33篇 |
社会与环境 | 15篇 |
灾害及防治 | 3篇 |
出版年
2023年 | 8篇 |
2022年 | 7篇 |
2021年 | 4篇 |
2020年 | 6篇 |
2019年 | 3篇 |
2018年 | 6篇 |
2017年 | 11篇 |
2016年 | 19篇 |
2015年 | 13篇 |
2014年 | 7篇 |
2013年 | 33篇 |
2012年 | 13篇 |
2011年 | 23篇 |
2010年 | 17篇 |
2009年 | 16篇 |
2008年 | 21篇 |
2007年 | 27篇 |
2006年 | 25篇 |
2005年 | 10篇 |
2004年 | 18篇 |
2003年 | 14篇 |
2002年 | 12篇 |
2001年 | 4篇 |
2000年 | 7篇 |
1999年 | 4篇 |
1998年 | 5篇 |
1997年 | 6篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1994年 | 4篇 |
1993年 | 5篇 |
1992年 | 6篇 |
1991年 | 5篇 |
1990年 | 8篇 |
1989年 | 6篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1984年 | 4篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1979年 | 7篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1970年 | 3篇 |
1960年 | 2篇 |
1954年 | 1篇 |
1953年 | 1篇 |
1935年 | 1篇 |
排序方式: 共有426条查询结果,搜索用时 31 毫秒
291.
292.
293.
Nicola Weber Stuart Bearhop Sasha R. X. Dall Richard J. Delahay Robbie A. McDonald Stephen P. Carter 《Behavioral ecology and sociobiology》2013,67(3):471-479
Heterogeneities in behaviours of individuals may underpin important processes in evolutionary biology and ecology, including the spread of disease. Modelling approaches can sometimes fail to predict disease spread, which may partly be due to the number of unknown sources of variation in host behaviour. The European badger is a wildlife reservoir for bovine tuberculosis (bTB) in Britain and Ireland, and individual behaviour has been demonstrated to be an important factor in the spread of bTB among badgers and to cattle. Radio-telemetry devices were deployed on 40 badgers from eight groups to investigate patterns of den (sett) use in a high-density population, where each group had one or two main and three to eight outlier setts in their territory. Badgers were located at their setts for 28 days per season for 1 year to investigate how patterns differed between individuals. Denning behaviour may have a strong influence on contact patterns and the transmission of disease. We found significant heterogeneity, influenced by season, sex and age. Also, when controlling for these, bTB infection status interacting with season was highly correlated with sett use. Test-positive badgers spent more time away from their main sett than those that tested negative. We speculate that wider-ranging behaviour of test-positive animals may result in them contacting sources of infection more frequently and/or that their behaviour may be influenced by their disease status. Measures to control infectious diseases might be improved by targeting functional groups, specific areas or times of year that may contribute disproportionately to disease spread. 相似文献
294.
295.
296.
297.
Stuart A. Altmann Stephen S. Wagner Sarah Lenington 《Behavioral ecology and sociobiology》1977,2(4):397-410
Summary Two models of conditions for the evolution of polygyny are treated axiomatically. Both models assume a social system based on female mate choice in situations in which a female is better off if she mates polygynously with an already mated male on a superior territory than if she selects a bachelor on an inferior territory. One model, the competitive female choice model, assumes that the females of a harem compete for the limited resources of the harem and thus that their fitness decreases as co-wives are added. The cooperative female choice model assumes that, within limits, a female's fitness is improved by the addition of co-wives to her mate's harem, as a result of cooperative interactions within the group. For each model, a sufficient set of independent assumptions is provided. Implications of the models are indicated and methods for testing them are discussed. 相似文献
298.
Levels and composition of volatile organic compounds on commuting routes in Detroit, Michigan 总被引:4,自引:0,他引:4
Stuart A. Batterman Chung-Yu Peng James Braun 《Atmospheric environment (Oxford, England : 1994)》2002,36(39-40)
Vehicle emissions can constitute a major share of ambient concentrations of many volatile organic compounds (VOCs) and other air pollutants in urban areas. Especially high concentrations may occur at curbsides, vehicle cabins, and other microenvironments. Such levels are not reflected by monitoring at fixed sites. This study reports on measurements of VOCs made from buses and cars in Detroit, MI. A total of 74 adsorbent tube samples were collected on 40 trips and analyzed by GC-MS for 77 target compounds. Three bus routes, selected to include residential, commercial and heavily industrialized areas, were sampled simultaneously on four sequential weeks during morning and afternoon rush hour periods. Nineteen compounds were regularly detected and quantified, the most prevalent of which included hexane/2-methyl pentane (15.6±5.8 μg m−3), toluene (10.2±7.9 μg m−3), m,p-xylene (6.8±4.7 μg m−3), benzene (4.5±3.0 μg m−3), 1,2,4-trimethylbenzene (4.0±2.6 μg m−3), o-xylene (2.2±1.6 μg m−3), and ethylbenzene (2.1±1.5 μg m−3). VOC levels in bus interiors and outdoor levels along the roadway were similar. Despite the presence of large industrial sources, route-to-route variation was small, but temporal variation was large and statistically significant. VOC compositions and trends indicate the dominance of vehicle sources over the many industrial sources in Detroit with the possible exceptions of styrene and several chlorinated VOCs. In-bus levels exceeded concentrations at fixed site monitors by a factor of 2–4. VOC concentrations in Detroit traffic are generally comparable to levels measured elsewhere in the US and Canada, but considerably lower than measured in Asia and Europe. 相似文献
299.
Alan E. Donnenfeld MD Johanna van de Woestune Frank Craparo Catherine S. Smith Avi Ludomirsky Stuart Weiner 《黑龙江环境通报》1991,11(4):235-244
Experience with three prenatally diagnosed pregnancies complicated by an acardiac twin reveals that ultrasonography and echocardiography are helpful in detecting early signs of in-utero congestive heart failure in the normal twin. The use of Doppler blood flow analysis to determine direction of blood flow, post-mortem placental and fetal angiography, and umbilical cord blood gas determination provided proof that retrograde arterial perfusion occurs in the acardiac fetus. In a fourth pregnancy, an experimental approach to occlude the acardiac twin's umbilical cord was attempted, but was unsuccessful. 相似文献
300.
W. K. Fitt S. L. Coon M. Walch R. M. Weiner R. R. Colwell D. B. Bonar 《Marine Biology》1990,106(3):389-394
Veliger larvae of the oysterCrassostrea gigas (Thunberg) responded to unknown dissolved chemical inducers found in supernatants of cultures of the bacteriaAlteromonas colwelliana andVibrio cholerae. The response, which was similar to that seen when larvae were exposed to the neurotransmitter precursor L-3,4-dihydroxyphenylalanine (L-DOPA), consisted of an initial settlement phase of swimming with the foot extended and crawling on the substrate. Subsequently larvae attached to the substrate and metamorphosed. The percentage of veligers metamorphosing following inducation of settlement behavior was higher in a group of older larvae, a response similar to that seen with L-DOPA, suggesting that competence to respond to bacterial supernatants is divided into two phases: behavioral competence followed by morphogenetic competence. Following size exclusion chromatography, the molecular weight of the peak containing the activity which induced settlement behavior was determined to be 300 daltons. Autoclaved Marine Broth, which induced low levels of settlement behavior also contained this low molecular weight active peak, suggesting that an oyster settlement inducer is also present in this medium.Contribution # 137 from the Center of Biotechnology, Marine Biotechnology Institute, University of Maryland, USA 相似文献